Liquid control valve

ABSTRACT

In order to achieve an object to provide a liquid control valve of normally close valve type which has both of an outflow side pressure automatic regulating function and a water stop function, the liquid control valve has a pressure regulating piston which moves within a housing for finding a balance point between an outflow side pressure and a spring force of a pressure regulating spring placed so as to resist the outflow side pressure; a movable valve seat which is provided in the pressure regulating piston and moves together with the pressure regulating piston; and a valve body which sits on the valve seat so as to close the valve in accordance with a valve closing force generated by an inflow side pressure and a spring force of a water stop spring, and moves apart from the valve seat so as to open the valve at the time when an external valve opening force larger than the valve closing force is applied, whereby the outflow side pressure automatic regulating function is achieved in accordance with movement of the pressure regulating piston, and the water stop function is achieved in accordance with the valve close.

This is a nationalization of PCT/JP02/03000 filed Mar. 27, 2002 andpublished in Japanese.

TECHNICAL FIELD

The present invention relates to a liquid control valve for controllinga flow of a liquid, and more particularly to a liquid control valvewhich has both of an outflow side pressure automatic regulating functionand a water stop function. The liquid control valve is, for example,used as a toilet bowl flush valve for supplying a washing water to atoilet bowl.

BACKGROUND ART

In conventional, as the liquid control valve having both of the outflowside pressure automatic regulating function and the water stop function,there is a known structure described in Japanese Utility ModelPublication No. 8-7456. However, this conventional art relates to avalve apparatus of normally open valve type which is open in the normalstate and is closed as occasion demands. Therefore, this apparatus has adisadvantage that this apparatus can not be used as it is for a toiletbowl flush valve of normally close valve type which is closed in thenormal state and is opened as occasion demands so as to supply thewashing water.

The present invention is made by taking the points mentioned above intoconsideration, and an object of the present invention is to provide aliquid control valve of normally close valve type which has both of anoutflow side pressure automatic regulating function and a water stopfunction.

In addition, another object of the present invention is to provide aliquid control valve in which a valve opening force is made small,whereby an excellent valve opening operability can be obtained. Further,another object of the present invention is to provide a liquid controlvalve which can achieve a throttling function at the time of closing thevalve, whereby it is possible to reduce generation of a water hammering.

DISCLOSURE OF THE INVENTION

In order to achieve the objects mentioned above, in accordance with afirst aspect of the present invention, there is provided a liquidcontrol valve comprising:

a pressure regulating piston which moves within a housing for finding abalance point between an outflow side pressure and a spring force of apressure regulating spring placed so as to resist the outflow sidepressure;

a movable valve seat which is provided in the pressure regulating pistonand moves together with the pressure regulating piston; and

a valve body which sits on the valve seat so as to close the valve inaccordance with a valve closing force generated by an inflow sidepressure and a spring force of a water stop spring, and moves apart fromthe valve seat so as to open the valve at the time when an externalvalve opening force larger than the valve closing force is applied,

wherein an outflow side pressure automatic regulating function isachieved in accordance with movement of the pressure regulating piston,and a water stop function is achieved in accordance with the valveclose.

Further, in accordance with a second aspect of the present invention,there is provided a liquid control valve as recited in the first aspectmentioned above, wherein a back pressure chamber is provided on the backsurface side of the valve body so as to introduce the outflow sidepressure to the back pressure chamber, and a valve opening directionpressure receiving surface portion is provided in the valve body so asto set an outer diameter of the valve opening direction pressurereceiving surface portion slightly smaller than an outer diameter of thevalve seat.

Further, in accordance with a third aspect of the present invention,there is provided a liquid control valve as recited in the first aspector the second aspect mentioned above, wherein a throttle is provided onthe side of the valve body so as to be arranged in an overlapping manneron the outer peripheral side of the movable valve seat provided in oneend of the pressure regulating piston and achieve a throttlingoperation.

In the liquid control valve in accordance with the first aspect of thepresent invention which is provided with the structure mentioned above,since the valve body sits on the valve seat so as to close the valve inaccordance with the valve closing force caused by the inflow sidepressure and the spring force of the water stop spring, and moves apartfrom the valve seat so as to open the valve at the time when theexternal valve opening force larger than the valve closing force isapplied, it is possible to construct the valve apparatus of normallyclose valve type which is closed in the normal state and is opened asoccasion demands. Further, since the pressure regulating piston moves soas to find the balance point between the outflow side pressure and thespring force of the pressure regulating spring at the time of openingthe valve, and the movable valve seat moves in correspondence to thismovement, a valve opening distance between the valve seat and the valvebody is automatically regulated in correspondence to a magnitude of theoutflow side pressure. Therefore, a flow amount can be automaticallyregulated in correspondence to the magnitude of the outflow sidepressure, and the outflow side pressure can be kept constant.

Further, in addition, in the liquid control valve in accordance with thesecond aspect of the present invention which is provided with thestructure mentioned above, since the back pressure chamber is providedon the back surface side of the valve body, in which the outflow sidepressure is introduced to the back pressure chamber, and the valveopening direction pressure receiving surface portion is provided in thevalve body, in which the outer diameter of the valve opening directionpressure receiving surface portion is set to be slightly smaller thanthe outer diameter of the valve seat, a magnitude of the valve closingforce in accordance with the inflow side pressure at the time of closingthe valve can be set comparatively small. Therefore, it is possible toset the magnitude of the external valve opening force to becomparatively small, in correspondence to this setting.

Further, in the liquid control valve accordance with the third aspect ofthe present invention which is provided with the structure mentionedabove, since the throttle is provided on the side of the valve body soas to be arranged in an overlapping manner on the outer peripheral sideof the movable valve seat provided in one end of the pressure regulatingpiston and achieve the throttling operation, the throttle overlaps thevalve seat at the time of closing the valve, whereby the flow amount canbe throttled little by little. Therefore, the flow amount and thepressure do not suddenly change, and it is thereby possible to restrictthe generation of water hammering.

In this case, the present application includes the following technicalmatters.

That is, in order to achieve the objects mentioned above, in accordancewith one liquid control valve (a pressure reducing valve with a waterstop apparatus) proposed by the inventors of the present application,there is provided a liquid control valve comprising:

one inflow port; and

one outflow port,

wherein a pressure regulating piston slides within a housing, a pressureregulating spring interposed between the pressure regulating piston andthe housing is operated by an outflow side pressure, the pressureregulating piston is operated, self-regulation works so that the outflowside pressure becomes constant, fluid pressure receiving areas in anaxial direction with respect to a valve piston are set so that apressure receiving area in a valve opening direction is a little smallerthan a pressure receiving area in a valve closing direction (it ispreferable that a difference in pressure receiving area is 0.5 cm² orless), and a valve opening force by a shaft is reduced.

Further, in accordance with another liquid control valve (a pressurereducing valve with a water stop apparatus), there is provided a liquidcontrol valve comprising:

one inflow port; and

one outflow port,

wherein a pressure regulating piston slides within a housing, a pressureregulating spring interposed between the pressure regulating piston andthe housing is operated by an outflow side pressure, the pressureregulating piston is operated, self-regulation works so that the outflowside pressure becomes constant, and a valve opening force by a shaft isreduced on the basis of a fluid pressure in the operation (axis)direction which is applied to a valve piston having a warping drum shapestructure which is constricted in the middle. Further, in the liquidcontrol valve as mentioned above, a throttle constructed in the valvepiston (this throttle is constructed by an independent part from thevalve piston, and can be constituted by a structure which is united inaccordance with a fixing method by a fixing hole formed on the outerperiphery, a hook formed in an outer peripheral portion of the valvepiston and the like), and a lip portion constructed in the pressureregulating piston are overlapped in the valve closing state, and arearranged with a certain clearance in a diametrical direction, thethrottle is formed so as to be open in a trumpet shape with respect to alip portion of the pressure regulating piston, and the lip portionconstructed in the pressure regulating piston is formed in an edge shapeat the front end along an outer peripheral portion.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional view of a liquid control valve in accordancewith an embodiment of the present invention;

FIG. 2 is a perspective view of a valve body in the control valve;

FIG. 3 is an exploded perspective view of the valve body in the controlvalve;

FIG. 4 is an enlarged cross sectional view of a main portion which showsa valve close state of the control valve;

FIG. 5 is an enlarged cross sectional view of the main portion whichshows a valve open state of the control valve;

FIG. 6 is an enlarged cross sectional view of the main portion whichshows a transitional state to close the control valve; and

FIG. 7 is a cross sectional view of a liquid control valve in accordancewith another embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Next, a description will be given of an embodiment in accordance withthe present invention with reference to the accompanying drawings.

FIG. 1 shows a cross section of a liquid control valve 1 in accordancewith an embodiment of the present invention. The control valve 1 isstructured as follows.

That is, first, a housing main body 3, a body 4, a cover 5 and an endcover 6 are combined in a water tight manner, and a housing 2constituted by these parts is provided. One inflow port 7 and oneoutflow port 8 for liquid are provided in the housing 2. The inflow port7 is provided on a side surface of the body 4, and is communicated withan inflow side pressure chamber 9 inside the body 4, and the outflowport 8 is provided on a side surface of the end cover 6, and iscommunicated with an outflow side pressure chamber 10 inside the endcover 6.

A pressure regulating piston 11 is arranged on the inner peripheral sideof the housing main body 3 in the housing 2 in such a manner as tofreely slide in the axial direction (the vertical direction in thedrawing). This pressure regulating piston 11 is structured such as tomove within the housing 2 so as to find a balance point between anoutflow side pressure (a secondary pressure) and a spring force of apressure regulating spring 12 which is placed so as to resist theoutflow side pressure. The pressure regulating piston 11 is formed in atubular shape, and moves in the axial direction along an innerperipheral surface of the housing main body 3 which is formed also in atubular shape. The pressure regulating spring 12 is arranged between thepressure regulating piston 11 and the housing main body 3 on the outerperipheral side of the pressure regulating piston 11, and elasticallyenergizes the pressure regulating piston 11 toward the outflow direction(the upward direction in the drawing).

A receiving space 13 between the pressure regulating piston 11 and thehousing main body 3 in which the pressure regulating spring 12 isarranged is open to the atmospheric air via vent holes 14 which areprovided in the housing main body 3 and the body 4. Further, in order toprevent the liquid flowing within the housing 2 from leaking into thespace 13, a portion between the pressure regulating piston 11 and thehousing main body 3 is sealed by a packing 15.

An inflow side end portion (a lower end portion in the drawing) of thepressure regulating piston 11 formed in the tubular shape is arrangedwithin the inflow side pressure chamber 9 so as to always protrude fromthe housing main body 3 into the inflow side (the lower side in thedrawing). A movable valve seat 16 formed in a ring shape is integrallyformed in an inflow side end portion of the pressure regulating piston11.

Further, a valve body 17 is arranged in the inflow side pressure chamber9 at a position of the inflow side of the valve seat 16 in such a manneras to freely slide in the axial direction. This valve body 17 isconstructed by combining a valve piston 18, a valve seat 19, a throttle20, a retainer 21, a packing 22 and an assembling screw 23, as shown inFIGS. 2 and 3. The valve piston 18 and the retainer 21 are fastened bythe assembling screw 23 in the state of holding the valve seat 19between the valve piston 18 and the retainer 21, and a claw-likeprojection 18 a provided in the valve piston 18 is engaged with a fixinghole 20 a provided in the throttle 20, whereby the throttle 20 is fixedto the valve piston 18. Further, a communication portion 24 formed in athrough hole shape is provided in the valve body 17 constructed by theseparts, in such a manner as to extend through an inner portion of thevalve body 17.

Returning to the description of FIG. 1, the retainer 21 of the valvebody 17 is slidably inserted to the inner peripheral side of thepressure regulating piston 11, and the lower end portion of the valvepiston 18 is slidably inserted to the inner peripheral side of the cover5 in the housing 2. Accordingly, the valve body 17 can move in the axialdirection as a whole, and the valve seat 19 is brought into contact withthe valve seat 16 at one end of the stroke of the valve body 17 so as toclose the valve.

The space within the cover 5 into which the valve piston 18 in the valvebody 17 is slidably inserted is formed as a back pressure chamber 25,and a water stop spring 26 for elastically energizing the valve body 17in the valve closing direction is arranged in the back pressure chamber25. Further, the back pressure chamber 25 is partitioned from the inflowside pressure chamber 9 by the packing 22 mentioned above, and since thecommunication portion 24 is provided in the valve body 17 as mentionedabove, the outflow side pressure is always introduced into the backpressure chamber 25.

In the control valve 1, a valve closing force for making the valve body17 sit on the valve seat 16 is constituted by a sum of a valve closingforce caused by an inflow side pressure (a primary pressure) which isintroduced into the inflow side pressure chamber 9 from the inflow port7, and a valve closing force caused by a spring force of the water stopspring 26. Between them, a magnitude of the valve closing force causedby the inflow side pressure is set to be comparatively small inaccordance with the following manner.

That is, a neck portion 18 b which is positioned substantially in themiddle of the outer peripheral surface of the valve piston 18 in theaxial direction and is formed in a shape having a reduced diameter, isprovided in the valve piston 18 of the valve body 17 arranged within theinflow side pressure chamber 9 mentioned above. A valve closingdirection pressure receiving surface portion 18 c is provided in theoutflow side (the upper side in the drawing) of the neck portion 18 b,and a valve opening direction pressure receiving surface portion 18 d isprovided in the opposite inflow side (the lower side in the drawing).The former valve closing direction pressure receiving surface portion 18c is structured such as to energize the valve body 17 toward the valveclosing direction at the time when the inflow side pressure is appliedto the valve closing direction pressure receiving surface portion 18 c,and the latter valve opening direction pressure receiving surfaceportion 18 d is structured such as to energize the valve body 17 towardthe valve opening direction at the time when the inflow side pressure isapplied to the valve opening direction pressure receiving surfaceportion 18 d. A pressure receiving area of the latter valve openingdirection pressure receiving surface portion 18 d is set to be smallerthan a pressure receiving area of the former valve closing directionpressure receiving surface portion 18 c, and an outer diameter φA of thevalve opening direction pressure receiving surface portion 18 d is setto be slightly smaller than an outer diameter φB of the valve seat 16.Accordingly, a valve closing force F generated by the inflow sidepressure at a time of closing the valve is set to be comparatively smallby the following formula.F=(SB−SA)×P  (1)

In this formula, SB is a substantial pressure receiving area in thevalve closing direction of the valve body 17 at the time of closing thevalve, SA is a substantial pressure receiving area in the valve openingdirection of the valve body 17 at the time of closing the valve, and Pis an inflow side pressure.

In accordance with this, a magnitude of a whole valve closing forcewhich is constituted by the sum of the inflow side pressure and thespring force of the water stop spring 26 is set to be comparativelysmall (in this case, in the drawing, since a cross section is cut by atreinforcing rib provided in the outer peripheral surface of the valvepiston 18 (since the reinforcing rib is described by a solid line and ahatching for showing the cross section is added), the neck portion 18 b,the valve closing direction pressure receiving surface portion 18 c andthe valve opening direction pressure receiving surface portion 18 d aredescribed by a dotted line in a whole or a part thereof).

On the contrary, a valve opening force for moving the valve body 17apart from the valve seat 16 is constituted by a pressing force in theaxial direction which is applied to the valve body 17 via a shaft (rod)27 from an external drive source (not shown), and when a magnitude ofthe external valve opening force becomes more than the magnitude of thevalve closing force mentioned above, the valve body 17 is operated so asto open the valve. The shaft 27 is held by the end cover 6 in thehousing 2 so as to freely slide in the axial direction. When the shaft27 moves in the inflow direction (the downward direction in the drawing)in the valve closing state, the shaft presses the valve body 17 so as toopen the valve. Further, when the shaft 27 moves in the outflowdirection (the upward direction in the drawing) in the valve openingstate, the valve body 17 is operated by the valve closing force so as toclose the valve.

In this case, in accordance with another embodiment, the shaft 27 may bearranged on the side of the back pressure chamber 25 which correspondsto the opposite side in the axial direction, as shown in FIG. 7. In thiscase, the shaft 27 pulls the valve body 17 at a time of opening thevalve.

Further, the annular valve seat 16 which is integrally formed at one endof the tubular pressure regulating piston 11 is structured such that anouter peripheral surface is formed into a straight surface in the axialdirection, and an inner peripheral surface is formed in a taper shape.Accordingly, the valve seat 16 is formed in a lip shape, the crosssection of which has a tapered edge shape. Further, the annular throttle20 which is provided in the valve body 17 as a part is arranged on theouter peripheral side of the valve seat 16 in an overlapping manner inthe axial direction so as to achieve a throttle operation with respectto the pressure at a time of closing the valve. The throttle 20 isformed so that the inner diameter has a clearance of 0.1 mm or less withrespect to an outer diameter of the valve seat 16, which is formed inthe lip shape, in the pressure regulating piston 11, and a lengththereof is 0.5 mm or more. Further, a tip thereof (a leading end portionof the inner peripheral surface) is formed in a taper shape, and isformed so as to be expanded in a trumpet shape.

The liquid control valve 1 having the structure mentioned above isconstructed as a valve apparatus of normally close valve type becausethe valve body 17 sits on the valve seat 16 so as to close the valve inaccordance with the valve closing force caused by the inflow sidepressure and the spring force of the water stop spring 26, as a mainportion thereof is shown in FIG. 4 in an enlarged manner, and movesapart from the valve seat 16 so as to open the valve only when theexternal valve opening force larger than the valve closing forcementioned above is applied, as shown in FIG. 5. Further, as shown inFIG. 6, at a time of opening the valve, the pressure regulating piston11 moves in the axial direction so as to find the balance point betweenthe outflow side pressure and the spring force of the pressureregulating spring 12, and the movable valve seat 16 integrally formed atone end of the pressure regulating piston 11 accordingly moves in theaxial direction. Therefore, a valve opening distance L between the valveseat 16 and the valve body 17 is automatically regulated incorrespondence to the magnitude of the outflow side pressure so that thevalve is widely opened at the time when the outflow side pressure ishigh, and the valve is narrowly opened at the time when the outflow sidepressure is low. Accordingly, a flow amount is automatically regulatedin correspondence to the magnitude of the outflow side pressure, and theoutflow side pressure is consequently kept constant, whereby there canbe achieved an outflow side pressure automatic regulating function ofautomatically keeping the magnitude of the outflow side pressure in afixed magnitude. Therefore, it is possible to provide the fluid controlvalve 1 of normally close valve type which has both of the outflow sidepressure automatic regulating function obtained by the movement of thepressure regulating piston 12, and the water stop function obtained bythe valve close mentioned above.

Further, in this liquid control valve 1, the back pressure chamber 25 isprovided on the back surface side of the valve body 17, in which theoutflow side pressure is introduced to the back pressure chamber 25 viathe communication portion 24 provided in the valve body 17, and thevalve opening direction pressure receiving surface portion 18 d isprovided in the valve body 17, in which the outer diameter φA of thevalve opening direction pressure receiving surface portion 18 d is setto be slightly smaller than the outer diameter φB of the valve seat 16.Accordingly, the magnitude of the valve closing force at the time ofclosing the valve is set to be comparatively small. Therefore, since themagnitude of the external valve opening force input from the externalcan be set to be comparatively small, it is possible to provide thefluid control valve 1 which can achieve an excellent valve openingoperability. In the case that the control valve 1 is used as the toiletbowl flushing valve, this valve opening operability is brought outparticularly as a response characteristic, and is great in a watersaving effect, a power saving effect and the like. Further, since theexternal drive source having a low output and a compact size can beused, it is possible to achieve a space saving and compactifying in awhole product. Further, in the case that the control valve 1 is used asthe toilet bowl flushing valve as mentioned above, it is preferable thatthe pressure receiving area difference (SB−SA) in the formula (1)mentioned above is set to be 0.5 cm² or less.

Further, in the control valve 1, since the throttle 20 is provided inthe valve body 17 as a part thereof, and the throttle 20 overlaps theouter peripheral side of the valve seat 16 during a step that the valveis going to close, it is possible to throttle the flow amount little bylittle on the basis of the throttling effect. Therefore, the flow amountand the pressure do not suddenly change, and it is accordingly possibleto prevent the water hammering from being generated. Further, even inthe case that the inflow side pressure is high, it is possible tosmoothly close the valve without generating any vibration. Further, theflow amount is throttled in the throttle 20, whereby the valve closingforce is generated in the portion having the diameter larger than thevalve seat 16, and the valve closing force larger than that in the caseof having no throttle is generated. Therefore, it is possible to improvea valve closing characteristic, and a stable valve closing motion can beobtained.

Further, in the control valve 1, in the case that the inflow sidepressure ascends abnormally in the water stop state, this abnormalpressure is relieved to the outflow side. Accordingly, the inflow sidehousing 2 does not require so much strength against the abnormalpressure. Therefore, a material of the housing 2 can be changed from aconventionally used metal to a comparatively brittle resin or the like,whereby it is possible to achieve a weight saving, a cost reduction andthe like in the product. In this relief mechanism, since the pressurereceiving area difference (SB−SA) in the formula (1) mentioned above isset minute as mentioned above, an increase in the seal surface pressure(a contact pressure between the valve body 17 and the valve seat 16) issmall even when the inflow side pressure is increased, whereby theabnormal pressure is generated by a leak from the portion between thevalve body 17 and the valve seat 16 when the pressure exceeds a certainvalue.

Further, in the control valve 1, since the valve seat 16, on which thevalve body 17 sits at the time of closing the valve, is provided in oneend portion of the pressure regulating piston 11 as the movable valveseat 16, it is not necessary to arrange a fixed valve seat in thehousing 2. Therefore, it is possible to simplify the shape of thehousing and make the housing 2 compact at this degree.

EFFECT OF THE INVENTION AND INDUSTRIAL APPLICABILITY

The present invention achieves the following effects.

That is, first, in the liquid control valve in accordance with the firstaspect of the present invention which is provided with the structurementioned above, since the valve body sits on the valve seat so as toclose the valve in accordance with the valve closing force caused by theinflow side pressure and the spring force of the water stop spring, andmoves apart from the valve seat so as to open the valve at the time whenthe external valve opening force larger than the valve closing force isapplied, it is possible to construct the valve apparatus of normallyclose valve type which is closed in the normal state and is opened asoccasion demands. Further, since the pressure regulating piston moves soas to find the balance point between the outflow side pressure and thespring force of the pressure regulating spring at the time of openingthe valve, and the movable valve seat moves in correspondence to thismovement, a valve opening distance between the valve seat and the valvebody is automatically regulated in correspondence to a magnitude of theoutflow side pressure. Therefore, a flow amount can be automaticallyregulated in correspondence to the magnitude of the outflow sidepressure, and the outflow side pressure can be kept constant.Accordingly, it is possible to achieve the outflow side pressureautomatic regulating function of automatically keeping the magnitude ofthe outflow side pressure constant. Therefore, it is possible to providethe fluid control valve of normally close valve type which has both ofthe outflow side pressure automatic regulating function on the basis ofthe movement of the pressure regulating piston and the water stopfunction caused by the valve close mentioned above.

Further, in this liquid control valve, since the valve seat, on whichthe valve body sits at the time of closing the valve, is provided in oneend of the pressure regulating piston as the movable valve seat, it isnot necessary to independently arrange the fixed valve seat in thehousing. Therefore, it is possible to simplify the shape of the housingand make the housing compact at this degree.

Further, in addition, in the liquid control valve in accordance with thesecond aspect of the present invention which is provided with thestructure mentioned above, since the back pressure chamber is providedon the back surface side of the valve body, in which the outflow sidepressure is introduced to the back pressure chamber, and the valveopening direction pressure receiving surface portion is provided in thevalve body, in which the outer diameter of the valve opening directionpressure receiving surface portion is set to be slightly smaller thanthe outer diameter of the valve seat, a magnitude of the valve closingforce in accordance with the inflow side pressure at a time of closingthe valve can be set comparatively small. Therefore, it is possible toset the magnitude of the external valve opening force which is inputfrom the external to be comparatively small, in correspondence to thissetting. Accordingly, it is possible to provide the liquid control valvewhich can achieve an excellent valve opening operability. In the casethat the control valve is used as the toilet bowl flushing valve or thelike, the valve opening operability is brought out particularly as aresponse characteristic, and is great in a water saving effect, a powersaving effect and the like. Further, since the external drive sourcehaving a low output and a compact size can be used, it is possible toachieve a space saving and compactifying in the product.

Further, in the liquid control valve in accordance with the third aspectof the present invention which is provided with the structure mentionedabove, since the throttle is provided in the valve body as a partthereof, and the throttle overlaps the outer peripheral side of thevalve seat during a step that the valve is going to close, it ispossible to throttle the flow amount little by little on the basis ofthe throttling effect. Therefore, it is possible to prevent the waterhammering from being generated due to the sudden change in pressure.Further, even in the case that the inflow side pressure is high, it ispossible to smoothly close the valve without generating any vibration.Further, the flow amount is throttled in the throttle, whereby the valveclosing force is generated in the portion having the diameter largerthan the valve seat 16, and the valve closing force larger than that inthe case of having no throttle is generated. Therefore, it is possibleto improve a valve closing characteristic, and a stable valve closingmotion can be obtained.

1. A liquid control valve comprising: a pressure regulating piston (11)which moves within a housing (2) for finding a balance point between anoutflow side pressure and a spring force of a pressure regulating spring(12) placed so as to resist the outflow side pressure; a movable valveseat (16) which is provided in the pressure regulating piston (11) andmoves together with the pressure regulating piston (11); and a valvebody (17) which sits on the valve seat (16) so as to close the valve inaccordance with a valve closing force generated by an inflow sidepressure and a spring force of a water stop spring (26), and moves apartfrom the valve seat (16) so as to open the valve at the time when anexternal valve opening force larger than the valve closing force isapplied, wherein an outflow side pressure automatic regulating functionis achieved in accordance with movement of the pressure regulatingpiston (11), and a water stop function is achieved in accordance withthe valve close.
 2. A liquid control valve as claimed in claim 1,wherein a back pressure chamber (25) is provided on the back surfaceside of the valve body (17) so as to introduce the outflow side pressureto the back pressure chamber (25), and a valve opening directionpressure receiving surface portion (18 d) is provided in the valve body(17) so as to set an outer diameter (φA) of the valve opening directionpressure receiving surface portion (18 d) slightly smaller than an outerdiameter (φB) of the valve seat (16).
 3. A liquid control valve asclaimed in claim 1, wherein a throttle (20) is provided on the side ofthe valve body (17) so as to be arranged in an overlapping manner on theouter peripheral side of the movable valve seat (16) provided in one endof the pressure regulating piston (11) and achieve a throttlingoperation.